// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_STREAMS_STREAM_REGISTRY_H_
#define CONTENT_BROWSER_STREAMS_STREAM_REGISTRY_H_

#include <stddef.h>

#include <map>
#include <set>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/threading/non_thread_safe.h"
#include "content/browser/streams/stream_register_observer.h"
#include "content/common/content_export.h"
#include "url/gurl.h"

namespace content {

class Stream;

// Maintains a mapping of blob: URLs to active streams.
class CONTENT_EXPORT StreamRegistry : public base::NonThreadSafe {
public:
    StreamRegistry();
    virtual ~StreamRegistry();

    // Registers a stream, and sets its URL.
    void RegisterStream(Stream* stream);

    // Clones a stream.  Returns true on success, or false if |src_url| doesn't
    // exist.
    bool CloneStream(const GURL& url, const GURL& src_url);

    void UnregisterStream(const GURL& url);

    // Called by Stream instances to request increase of memory usage. If the
    // total memory usage for this registry is going to exceed the limit,
    // returns false. Otherwise, updates |total_memory_usage_| and returns true.
    //
    // |current_size| is the up-to-date size of ByteStream of the Stream instance
    // and |increase| must be the amount of data going to be added to the Stream
    // instance.
    bool UpdateMemoryUsage(const GURL& url, size_t current_size, size_t increase);

    // Gets the stream associated with |url|.  Returns NULL if there is no such
    // stream.
    scoped_refptr<Stream> GetStream(const GURL& url);

    void set_max_memory_usage_for_testing(size_t size)
    {
        max_memory_usage_ = size;
    }

    void SetRegisterObserver(const GURL& url, StreamRegisterObserver* observer);
    void RemoveRegisterObserver(const GURL& url);

    // If the reader is aborted before the stream is registered, call this method
    // to reduce the memory consumption. After this method is called,
    // RegisterStream doesn't register the stream of the URL.
    void AbortPendingStream(const GURL& url);

private:
    typedef std::map<GURL, scoped_refptr<Stream>> StreamMap;

    StreamMap streams_;
    std::map<GURL, StreamRegisterObserver*> register_observers_;
    std::set<GURL> reader_aborted_urls_;

    size_t total_memory_usage_;

    // Maximum amount of memory allowed to use for Stream instances registered
    // with this registry.
    size_t max_memory_usage_;

    DISALLOW_COPY_AND_ASSIGN(StreamRegistry);
};

} // namespace content

#endif // CONTENT_BROWSER_STREAMS_STREAM_REGISTRY_H_
